Technological development and increased demand for mobile equipment have led to a sharp rise in the demand for secondary batteries as energy sources. Among these secondary batteries, lithium secondary batteries having high energy density and driving voltage, long cycle lifespan and low self-discharge are commercially available and widely used.
In addition, increased interest in environmental issues has brought about a great deal of research associated with electric vehicles (EVs) and hybrid electric vehicles (HEVs) as alternatives to vehicles using fossil fuels such as gasoline vehicles and diesel vehicles which are major causes of air pollution. Nickel-metal hydride (Ni-MH) secondary batteries are generally used as power sources of electric vehicles (EVs) and hybrid electric vehicles (HEVs). However, a great deal of study associated with use of lithium secondary batteries with high energy density, high discharge voltage and power stability is currently underway and some of such lithium secondary batteries are commercially available.
A lithium secondary battery has a structure in which a non-aqueous electrolyte comprising a lithium salt is impregnated into an electrode assembly comprising a cathode and an anode, each comprising an active material coated onto a current collector, and a porous separator interposed therebetween.
In general, a method including applying a slurry-type electrode mix to an electrode current collector, followed by drying and pressing is used for production of an electrode for secondary batteries. In addition, an electrode active material, a conductive material and a binder are added to a solvent, followed by homogeneously mixing in order to prepare the slurry-type electrode mix.
In this process, the electrode active material or the like may be used in the form of considerably small particles. In this case, fine particles agglomerate, thus disadvantageously inhibiting homogenization. In order to solve this problem, mixing time may be lengthened. However, disadvantageously, this mixing time serves as a bottleneck in the overall process.
Accordingly, there is an increasing need for methods capable of homogeneously mixing fine particles.